feat(claude): Support calling Claude channels via /v1/responses

[Redtropig]

(incl. OpenAI function call --> Claude tool use)
Set "ChatCompletions→Responses 兼容配置" && "Model mapping" to test.

• Implement ConvertOpenAIResponsesRequest and DoResponsesRequest in Claude adaptor to support the experimental OpenAI Responses API.
• Add RequestOpenAIResponses2ClaudeMessage to convert Responses inputs to Claude messages, featuring validation to skip empty text blocks causing API errors.
• Implement response conversion logic in ResponseClaude2OpenAIResponses, correctly mapping Claude's tool_use to function_call outputs.
• Update ResponsesResponseToChatCompletionsResponse in compatibility service to support messages containing both text and tool calls, ensuring reasoning text is not discarded when tools are used.

-> Tested working config:

Summary by CodeRabbit

• New Features

  • Added Claude backend support for OpenAI-style "responses" requests, including request/response translation, routing so "responses" mode uses the Claude pathway, and streaming (SSE) support with conversion to OpenAI-style streaming.

• Bug Fixes

  • Improved tool/function-call handling: tool_calls are captured even when text is present and assistant content is no longer cleared.